Python:更新类函数中嵌套字典的值

class MyClass:
    def __init__(self):
        self.my_dict = {'key1': {'nested_key1': 'value1', 'nested_key2': 'value2'},
                        'key2': {'nested_key3': 'value3', 'nested_key4': 'value4'}}

    def update_nested_dict(self, key, nested_key, new_value):
        if key in self.my_dict and nested_key in self.my_dict[key]:
            self.my_dict[key][nested_key] = new_value
            return True
        return False

my_instance = MyClass()
my_instance.update_nested_dict('key1', 'nested_key1', 'new_value')